Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Angiotensin II (AII) can release arachidonic acid metabolites such as prostacyclin (PGI2) and PGE2 from cells in cultures. It has recently been reported that the AT1 selective nonpeptide AII receptor antagonist losartan had similar effects. The present study was undertaken to further evaluate the effects of AII and losartan on cells which synthesize prostaglandins, including vascular smooth muscle, endothelial, and glial cells. Inhibition of specific [125I]AII binding was demonstrated in porcine smooth muscle cell (PSMC) suspensions with unlabeled AII and losartan. The IC50 values were 1.3 x 10(-9) mol/L and 7.7 x 10(-9) mol/L, respectively. PD123177 (an AT2 selective antagonist) had no effect on binding. AII produced a concentration-related increase in calcium mobilization (fura-2 fluorescence) which was blocked by losartan (IC50 = 8.4 x 10(-8) mol/L) but not by PD123177 (10(-6) mol/L). AII (10(-7) to 10(-5) mol/L) stimulated the basal release of PGI2 by 100%. This response was blocked by losartan (10(-6) to 10(-5) mol/L) but not by PD123177 (10(-6) to 10(-5) mol/L) and neither agent stimulated basal release in PSMC. Similar effects of AII and antagonists were observed upon receptor binding and PGE2 release in primary rat astrocyte (RA) cultures. AII did not release PGI2 from porcine endothelial cells, bovine pulmonary arterial endothelial cells, or rat C6 glioma cells. Losartan had no significant effect at 10(-5) mol/L. By contrast, bradykinin or the calcium ionophore A23187 dramatically increased PGI2 release in each of these cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:AT1 receptors mediate the release of prostaglandins in porcine smooth muscle cells and rat astrocytes. 141 54

Human glioblastoma cells secrete factors, such as prostaglandin E (PGE) and transforming growth factor beta type 2, which are capable of suppressing several immune functions. The present study investigated the effect of PGE2 and agents known to increase intracellular cyclic adenosine monophosphate (cAMP) levels on 1) the induction of lymphokine-activated killer (LAK) cell activity from the peripheral blood lymphocytes (PBL) of both normal and glioma patients and on 2) the cytolytic activities of tumor-infiltrating lymphocytes (TIL's) isolated from malignant gliomas after expansion in vitro with interleukin-2 (IL-2). Cytolytic activity was measured against autologous and allogeneic tumor cells and the natural killer-resistant Daudi cell line. The results demonstrate that PGE2 and agents known to increase intracellular cAMP levels can significantly suppress the IL-2-dependent generation of cytolytic activity from the PBL of normal and glioma patients and from glioblastoma-derived TIL's. The inhibitory effects of these agents could not be reduced by higher concentrations of IL-2 or by cyclic guanosine monophosphate. Although the suppressive effect of PGE2 was most significant during the early stages of LAK cell generation, an inhibitory effect was still evident when PGE2 was added directly to the cytotoxicity assay. Secretion of PGE2 by glioblastoma cells in vivo may regulate both the generation of an immune response and the effectiveness of adoptively transferred immune cells.
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PMID:Influence of PGE2- and cAMP-modulating agents on human glioblastoma cell killing by interleukin-2-activated lymphocytes. 196 67

The heptapeptide angiotensin (ANG)-(1-7) mimics some but not all the central actions of ANG II, suggesting that receptor subtypes may exist. The effects of ANG-(1-7), ANG II, and ANG I on prostaglandin (PG) E2 and prostacyclin (PGI2) synthesis were investigated in neurally derived rat C6 glioma cells. All three ANG peptides stimulated PG release in a dose-dependent manner with the order of potency ANG-(1-7) greater than ANG I greater than ANG II. PGE2 release induced by ANG-(1-7) (10(-7) M) was partially blocked by [Sar1,Ile8]ANG II (10(-6) M), [Sar1,Thr8]ANG II (10(-6) M), or the subtype 1 selective antagonist Du Pont 753 (10(-5) M) but not by the subtype 2 selective antagonist CGP 42112A (10(-7)-10(-5) M). PGI2 release was inhibited only by [Sar1,Thr8]ANG II. ANG II-induced PGE2 release was blocked by [Sar1,Thr8]ANG II (10(-6) M), [Sar1,Ile8]ANG II (10(-6) M), or Du Pont 753 (10(-7) M) but not by CGP 42112A (10(-7)-10(-5) M). In contrast, ANG II-induced PGI2 release was blocked by Du Pont 753 (10(-7) M) as well as [Sar1,Ile8]ANG II (10(-6) M) but not by [Sar1,Thr8]ANG II or CGP 42112A. Thus ANG II-stimulated PGE2 and PGI2 syntheses in C6 glioma cells are mediated via receptor subtype 1. ANG-(1-7)-induced PGE2 synthesis is also mediated via subtype 1 receptors; however, PGI2 release was blocked by [Sar1,Thr8]ANG II only.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Characterization of angiotensin receptors mediating prostaglandin synthesis in C6 glioma cells. 203 93

In an attempt to define the angiotensin II receptor subtype responsible for prostaglandin release, we studied the effects of the nonpeptide, subtype 1 (or B) selective angiotensin II antagonist, DuP 753. Release of prostaglandin E2 produced by angiotensin II from rat C6 glioma, human astrocytoma, or porcine aortic smooth muscle cells in culture was blocked by the addition of the 10(-7) M of DuP 753. In contrast, the release of prostacyclin, as assessed by measurement of the stable metabolite 6-keto PGF1 alpha, was not attenuated by addition of Du P 753. However, DuP 753 either alone or in combination with angiotensin II, produced dose-dependent increases in prostacyclin release with doses as low as 10(-8) M. In the absence of angiotensin II, DuP 753 also increased prostaglandin E2 release at high doses but the magnitude of the potentiation was substantially less than for prostacyclin release (50 to 250% v 400 to 2800% above basal). Thus, we clearly show that angiotensin II stimulates PGE2 release via subtype 1 (or B) angiotensin receptors. Whether the effect of DuP 753 on prostaglandin release is a result of agonistic properties or intrinsic effects unrelated to blockage of angiotensin II receptors remains to be determined. The marked stimulatory effect of DuP 753 release precludes characterization of the receptor subtype that mediates the Ang II-induced release of prostacyclin. Nonetheless, potent stimulation of prostacyclin release by DuP 753, especially in vascular smooth muscle cells, requires reevaluation of the mechanisms that participate in the anti-hypertensive effects of the compound.
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PMID:The nonpeptide angiotensin II antagonist DuP 753 is a potent stimulus for prostacyclin synthesis. 204 99

In the process of malignant transformation, astrocytoma cells display a number of surface antigens not expressed by their normal adult counterparts and which have been identified by monoclonal antibodies and characterized biochemically. These include tumor associated antigens (TAA) such as oncofetal antigens of neuroectodermal origin or oncogene products such as epitopes in the extracellular domain of the epidermal growth factor receptor, as well as major histocompatibility antigens (MHC) of class I and class II. Glioma cells also secrete lymphokines like IL-1 and IL-6. The concomitant expression of TAA and MHC together with the disruption of the blood brain barrier may elicit a humoral or cell mediated immune response from the tumor bearing host as demonstrated by the functional analysis of tumor infiltrating lymphocytes. However this response is extremely weak and obviously inefficient because the tumor cells secrete factors which can inhibit or completely abrogate the immune attack by cytotoxic T cells. Among these factors, TGF-beta 2 and PGE2 are of particular interest since they may explain the generally depressed cellular immune response observed in patients with malignant gliomas. To be efficient any form of immunotherapy will require abatement of these suppressive activities in addition to stimulation of the effector functions.
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PMID:Immunotherapy of brain tumors. 209 5

The effects of prostaglandin D2 (PGD2) on the growth of mouse malignant glioma cells were studied in vitro and in vivo. The in vitro studies consisted of various concentrations of prostaglandins (PG's) being added to cultures of mouse glioma cells. At concentrations above 2.5 micrograms/ml, PGD2 strongly inhibited the proliferation of glioma cells, whereas PGE2 had no effect at the same value. Exposure to 5.0 micrograms/ml PGD2 for more than 2 hours resulted in inhibition of glioma cell proliferation. This growth-inhibitory effect of PGD2 was related to the inhibition of DNA synthesis of the cells. The in vivo studies were performed with a subcutaneously transplanted mouse glioma model. Injection of 0.5 mg/kg PGD2 into the tumor was more effective than the same concentration given by intraperitoneal injection. In mice with intracranially transplanted glioma, daily intraperitoneal injection of 0.5 mg/kg PGD2 had no significant effect on survival time.
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PMID:Growth-inhibitory effect of prostaglandin D2 on mouse glioma cells. 649 36

In 16 patients with primary supratentorial and in 1 with cerebellar tumor among them 5 multiforme glioblastomas, 3 malignant astrocytomas, 6 astrocytomas of other subtypes and 1 mixed glioma (oligo-astrocytoma) the peripheral blood was drawn and lymphocytes were separated from it. Out of the removed part of the tumors about 10 cultures in each case were prepared and cultivated at least 14 days. When the growth zone was well developed the cultures were used for further studies. All samples of the separated lymphocytes activated with PHA were cultivated for 72 h. So prepared lymphocytes were added to the tumor culture in vitro and observed for 24 h. After that time the not adhered lymphocytes were removed and the remaining tissue cultures with adhered lymphocytes were fixed and stained and the number of lymphocytes was counted. It was found that 1 h after the addition of lymphocytes the number of lymphocytes was very high, though a great part of them did not adhere to the tumor tissue. After 24 h the number of adhered lymphocytes was small or minute. Taking into consideration the results obtained it seems that the low efficiency of therapy of gliomas with autologous lymphocytes in vivo can result from the very weak direct contact with tumor cells. The influence of lymphocytes can be very limited so more as the tumor cells can secret biological active substances like PGE2, which counteract the cytotoxic activity of lymphocytes. For that reason the number of lymphocytes can be of significant value as counterbalance to that properties of the tumor cells. Taking into account even secretion of tumor cells of the same biological active substances such as PGE2 which counteract the cytotoxic activity of lymphocytes for the efficient activity of lymphocytes the number of them may be of significant value.
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PMID:Some remarks on adherence reactivity of autologous PHA--transformed lymphocytes on human glial tumor cells in vitro. 792 99

The molecular pathways by which the cyclopentenone prostaglandins (PGA and PGJ series) inhibit cell growth and tumorigenicity are poorly understood. These cellular responses may be caused by specific regulation of growth-related and stress-induced genes. A variety of prostaglandins were tested for their ability to regulate insulin-like growth factor-I (IGF-I) and Waf1 gene expression in C6 rat glioma cells. The prostaglandins (in order of potency) PGJ2 > PGA1 > PGA2, approximately PGD2 >> PGE2 all significantly repressed IGF-I gene expression. With the exception of PGE2, the same prostaglandins that repressed IGF-I also induced Waf1 gene expression. However, the order of potency for Waf1 induction was different than for IGF-I repression: PGA2 > PGA1 approximately PGJ2 > PGD2. The different order of potency of the prostaglandins in regulating IGF-I and Waf1 gene expression suggests that different intracellular signals may be involved in regulating the two genes. Augmentation of glutathione levels by pretreatment of cells with N-acetyl-L-cysteine attenuated the effect of PGA2 on IGF-I and Waf1 gene expression. conversely, depletion of the intracellular glutathione pool by pretreatment with buthionine sulfoximine potentiated the effect of PGA2 on the expression of both genes. These results suggest that conjugation with glutathione prevents the regulation of gene expression by PGA2. We also tested the effect of several simpler compounds that contain a five-membered ring system on IGF-I and Waf1 gene expression. 2-Cyclopenten-1-one, but not cyclopentene or cyclopentene, repressed IGF-I and induced Waf1 gene expression, demonstrating the requirement for an alpha, beta-unsaturated carbonyl for regulation of the two genes. The dione compound 4-cyclopentene-1,3-dione, which has two potentially reactive carbons rather than one, was considerably more potent than 2-cyclopentene-1-one in repressing IGF-I gene expression (IC50 = 30 microM for 4-cyclopentene-1,3-dione as compared with 167 microM for 2-cyclopentene-1-one). Additional results indicated that diethyl maleate, which has two alpha,beta-unsaturated carbonyls in a non-cyclic configuration, also repressed IGF-I gene expression (IC50 = 214 microM) and induced Waf1 gene expression, indicating that the cyclic structure is not required for either effect.
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PMID:Effects of cyclopentenone prostaglandins and related compounds on insulin-like growth factor-I and Waf1 gene expression. 954 24

Taurine prevents tissue damage in various models of inflammation through a mechanism postulated to involve taurine monochloramine (Tau-Cl). Tau-Cl is formed through the action of a halide-dependent myeloperoxidase system associated with polymorphonuclear leukocytes (PMN), eosinophils, and basophils. Production of nitric oxide (NO), PGE2, and other proinflammatory mediators by activated macrophages is inhibited by Tau-Cl. Since glial cells may be activated to produce NO, PGE2 and other proinflammatory mediators, similar to macrophages, we examined the effects of Tau-Cl on the production of NO and PGE2 by rat C6 glioma cells. C6 cells were seeded to grow over 2-3 days to approximately 90% confluency before exposure to various concentrations of Tau-Cl in HBSS for 2 h (37 degreesC, 5% CO2). The HBSS was replaced, after washing the cells, with DMEM containing 4% fetal calf serum and activators (LPS, 10 microgram/ml; rat rIFN-gamma, 50 U/ml; and human rTNF-alpha, 50 ng/ml). Media content of NO2- and PGE2 was measured 48 h after activation and cell lysates were subjected to SDS-PAGE followed by Western blot analyses to determine the relative expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins. Media accumulation of NO2- and PGE2 was inhibited by Tau-Cl in a concentration dependent manner and this was accompanied by decreased amounts of iNOS and COX-2 proteins in cell lysates. Additional experiments determined the effects of Tau-Cl on the kinetics of iNOS and COX-2 mRNA expression. Expression of iNOS mRNA was markedly inhibited in activated C6 cells that were previously exposed to Tau-Cl and this persisted for at least 24 h. In contrast, inhibition of COX-2 mRNA expression was only transiently reduced in Tau-Cl exposed cells during the first 4 h of activation and was relatively unimpaired thereafter (8-24 h). These results suggest that Tau-Cl inhibits the transcriptional expression of the iNOS gene but inhibits expression of COX-2 protein by post-transcriptional mechanisms.
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PMID:Taurine chloramine inhibits production of nitric oxide and prostaglandin E2 in activated C6 glioma cells by suppressing inducible nitric oxide synthase and cyclooxygenase-2 expression. 972 77

Malignant rat T9 glioma cells retrovirally transduced with the membrane form of macrophage colony stimulating factor (mM-CSF) were killed by bone marrow derived macrophages in 24 h cytotoxicity assays. Prostaglandin E2 (PGE) and interleukin-10 (IL10) were tested for their ability to block this tumoricidal reaction. Only at very high nonphysiological concentrations of PGE (10(-5) and 10(-6) M) was this cytotoxicity inhibited. Use of high doses of theophylline, a phosphodiesterase inhibitor, also prevented macrophages from killing the mM-CSF transduced target cells. IL10 did not alter the killing potential of the mM-CSF tumoricidal macrophages, even though IL10 reduced the production of nitric oxide by macrophages in response to tumor necrosis factor and lipopolysaccharide. IL10 enhanced the growth of bone marrow macrophages suggesting that IL10 has a complex role in the regulation of tumoricidal macrophages. Thus, the mM-CSF may be an ideal agent to treat tumors that utilize either of these two immunosuppressive defense mechanisms that may block other forms of treatment.
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PMID:Macrophages that kill glioma cells expressing the membrane form of macrophage colony stimulating factor are resistant to prostaglandin E2 and interleukin-10. 1054 Oct 53


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